A physical unclonable function (PUF) provides, for example, a digital value that can serve as a unique identity for a semiconductor device, such as a microprocessor. PUFs are based, for example, on physical variations which occur naturally during semiconductor manufacturing, and which permit differentiating between otherwise identical semiconductor chips.
PUFs are typically used in cryptography. A PUF can be, for example, a physical entity that is embodied in a physical structure. PUFs are often implemented in integrated circuits, and are typically used in applications with high security requirements. For example, PUFs can be used as a unique and untamperable device identifier. PUFs can also be used for secure key generation, and as a source of randomness.